泡沫碳表面对高超声速边界层稳定性影响

Hypersonic boundary-layer transition generates a significant increase in skin friction and heat flux, which leads to severe restrictions on the performance of hypersonic vehicles. Micropore surfaces have a significant deal of potential for application since they can successfully prevent boundary layer transition without clearly altering the average flow field.The effects of carbon foam material on unstable modes in hypersonic boundary-layer are studied in Mach 6 Ludwieg wind tunnel, the experimental results indicate that there exists an obvious second mode wave in the boundary layer, and its characteristic frequency decreases downstream. The carbon foam surface, when compared to a smooth surface, at various streamwise positions retards the formation of the second mode wave and increases the second mode propagation area by at least 21.6%. In addition, the impedance tube is used to measure the acoustic characteristics of the carbon foam surface to obtain impedance model coefficients. The linear stability theory is used to predict the growth rate of disturbance mode on the carbon foam surface, and the theoretical results have the same trend as the experimental results.